Method of assembling panelized aircraft fuselages

ABSTRACT

A method of assembling a panelized aircraft fuselage comprises loading a keel structure on a cradle; attaching stanchions to a floor grid; positioning the floor grid and stanchions over the keel structure and attaching the stanchions to the keel structure; obtaining a full fuselage contour including locating lower panels on the floor grid while using the cradle, the floor grid, and the keel structure to support the lower panels, and locating upper panels on the lower panels; and fastening the lower panels to the keel structure and the upper panels. The fuselage is assembled upright from the keel structure without changing orientation of the fuselage.

BACKGROUND

A commercial aircraft fuselage may have a panelized skin construction.For example, a panelized fuselage may include fuselage panels such ascrown, side and keel panels attached to a frame. The crown panel isprimarily subject to tension loading, the side panels are subjectlargely to shear and pressure load redistribution around windows anddoors, and the keel is subject primarily to axial compression and loadredistribution from a keel beam.

Facilities for assembling panelized fuselages of large commercialaircraft may include large floor spaces with jigs and fixtures securedto the floor. These jigs and fixtures are used to assemble the variouspanels into fuselages.

The assembly of panelized fuselages of large commercial aircraft is verylabor intensive. Due to a heavy dependence on manual labor, productionrates are subject to constant change. Changes in production rates canlengthen production times.

It would be desirable to create a more stable environment for assemblingthe fuselages of large commercial aircraft.

SUMMARY

According to an embodiment herein, a facility for assembling aircraftfuselages comprises a plurality of movable cradles. Each cradle isconfigured to support a fuselage keel structure and assemble a panelizedfuselage in a single upright build position.

According to another embodiment herein, a method of assembling aplurality of aircraft fuselages comprises moving movable cradles todifferent locations on an assembly floor, and using the cradles toassemble panelized fuselages upwards without changing orientations ofthe fuselages.

According to another embodiment herein, a method of assembling apanelized aircraft fuselage comprises loading a keel structure on acradle, attaching stanchions to a floor grid, positioning the floor gridand stanchions over the keel structure and attaching the stanchions tothe keel structure, and locating lower panels on the floor grid. Thecradle, the floor grid, and the keel structure are used to support thelower panels.

These features and functions may be achieved independently in variousembodiments or may be combined in other embodiments. Further details ofthe embodiments can be seen with reference to the following descriptionand drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a facility for assembling aircraftfuselages.

FIGS. 2A-2T are illustrations of an example of assembling a plurality offuselages.

FIG. 3 is an illustration of a robot for performing fuselage fasteningoperations.

FIG. 4 is an illustration of a one-up fastening operation.

FIG. 5 is an illustration of a method of performing an upright build ofa fuselage.

FIGS. 6A-6E are illustrations of a fuselage during various phases of anupright build process.

DETAILED DESCRIPTION

Reference is made to FIG. 1, which illustrates an automated facility 110for assembling aircraft fuselages. The facility 110 includes an assemblyfloor 120. For example, the floor 120 may include one or more thickconcrete slabs with appropriate load bearing capability. The slabs maybe relatively flat and smooth. Unlike a conventional assembly facility,the facility 110 does not have fuselage assembly jigs and fixturessecured to the floor 120.

In some embodiments, the assembly floor 120 is large enough toaccommodate multiple assembly areas or assembly cells. Within eachassembly cell, a fuselage may be assembled. Multiple assembly cellsallow multiple fuselages to be assembled at the same time.

The facility 110 further includes a plurality of movable cradles 130.Each cradle 130 is configured to support a fuselage keel structure andassemble a panelized fuselage in a single upright build position. Asingle upright build position of a panelized fuselage refers to aprocess that starts with a keel structure and adds panels upwardswithout changing orientation of the fuselage.

In some embodiments, each cradle 130 may be moved across the assemblyfloor 120 by an automated guided vehicle (AGV). In other embodiments,each cradle 130 may be moved across the floor 120 by a crane or forktruck.

The facility 110 further includes a gantry 140 for moving fuselagepanels and other structures across the floor 120 to selected assemblycells. For instance, the gantry 140 may include cranes for picking upfuselage panels or floor grids at a first location, and placing thepanels or floor grids onto cradles 130 of selected assembly cells.

The facility 120 also includes a plurality of robots 150 for performingfuselage fastening operations. Examples of fuselage fastening operationsinclude, but are not limited to, drilling, fastener insertion, andfastener termination.

The robots 150 are movable into position alongside cradles 130 inselected cells. Consider an example in which first and second cradles130 are in service for assembling first and second fuselages. Somerobots 150 of the plurality are moved across the floor 120 into positionalongside the first cradle, while other robots 150 of the plurality aremoved across the floor 120 into position alongside the second cradle130. Still other robots 150 may be at other locations on the assemblyfloor 120. Still other robots may be located in storage or in amaintenance depot.

In some embodiments, each robot 150 may be moved across the floor 120 byan automated guided vehicle (AGV). In other embodiments, each robot 150may be moved across the floor 120 by a combination of AGV and manualassisted vehicles (e.g., a crane, a fork truck). Either AGV or manualassisted vehicles may be used to move the robots 150 across the floor120 to a selected cell. (During operation, AGV is used to move therobots 150 along the length and circumference of a fuselage to completedrilling and fastening tasks in multiple zones.)

Some embodiments of the facility 110 may further include a controlcenter 160 for controlling the placement, sequencing, and operation ofthe cradles 130, gantry 140, and robots 150. The control center 160 mayinclude a computer system and it may be located above the assembly floor120 with a high view for operations personnel and camera systems tovisually observe the assembly operations. The cradles 130, gantry 140,robots 150 may communicate wirelessly with the control center 160. Thecontrol center 160 may also be responsible for controlling the robots150 to avoid collisions and disruptions of automated manufacturingoperations; determining when one robot 150 needs to be replaced withanother robot 150 from the storage or maintenance depot; and makingrepair/replacement decisions on any non-conformances occurring duringdrilling/fastening operations on the fuselages.

In other embodiments, the cradles 130, gantry 140 and robots 150 may beprogrammed with artificial intelligence, which enables these systems toperform certain operations autonomously. The autonomous operationreduces the burden of central control, and distributes some of theburden to the cradles 130, gantry 140 and robots 150.

FIGS. 2A to 2T illustrate an example in which multiple fuselages areassembled by the automated facility 110. Control of the cradles 130,gantry 140 and robots 150 may be performed solely by the control center160 or by a combination of central control and autonomous control.

FIG. 2A illustrates an example of a facility 110 having a single gantry140 and an assembly floor 120 that has six assembly cells 210, a feederline area 220, and a robot holding area 230. The cells 210 do not haveany fuselage assembly jigs or fixtures secured to the floor 120. Eachcell 210 only has markings for indicating cradle positions, robot paths,etc. The assembly floor 120 may be marked with paint, tape, RFID tagsembedded in the floor 120, laser projections, etc. As will be explainedbelow, the markings need not be precise.

The feeder line area 220 is the area where fuselage materials arereceived. It is also the area where built-up fuselages are delivered.

Idle robots 150 are located in the robot holding area 230. In thisexample, the robots 150 include two different types: tall robots 150 athat perform longitudinal splices over the entire fuselage andcircumferential splices on the upper portion of a fuselage (e.g., to thetop of the crown at stringer 0); and short robots 150 b that performcircumferential splices on the lower portion of a fuselage. Each robot150 a and 150 b may be moved by an AGV. An AGV may find a cell 210 basedon preprogrammed paths and assembly floor markings.

FIG. 2A does not show any cradles 130, nor does it show the controlcenter 160. FIG. 2A shows the facility 110 prior to the assembly of anyfuselages. The assembly floor 120 is vacant.

FIG. 2B shows the beginning of the assembly of a first fuselage. A firstcradle 130 is moved (via an underlying AGV) into the feeder line area220.

FIG. 2C shows the first cradle 130 after it has been moved into a firstone of the six assembly cells 210. The cradle 130 may be positioned withrespect to precise markings on the floor 120 of that first assembly cell210. In this example, the first cradle 130 is moved into the lowerleftmost cell 210. However, it could have been moved into any one of theother five cells 210. The selection of the assembly cell 210 is notrandom but rather based on rate and firing order (which determines theoptional hardware that was ordered by the customer). This selectioncontrols the path and timing of all the movements by the AGVs in orderto avoid collisions.

As the first cradle 130 is being moved into the selected assembly cell210, fuselage components may be moved to the feeder line area 220. FIG.2C shows a fore keel structure located in the feeder line area 220. Thefore keel structure and subsequent components may be transferred to thefeeder line area 220 in large transportation/shipping fixtures, whichmay be moved by fork trucks. After the first cradle 130 is moved to theselected assembly cell 210, the AGV 135 that moved it is returned to thefeeder line area 220.

FIG. 2D shows the gantry 140 positioned over the fore keel structure.The gantry 140 raises the fore keel structure and moves that structureover the cradle 130, and lays the fore keel structure onto the cradle130, as shown in FIG. 2E. The gantry 140 is automated up to the deliveryof the structure to the assembly cell 210. Once the keel structure islocated over the cradle 130, the gantry 130 may be controlled manuallyto lower the keel structure onto the cradle 130. The gantry 140 may havea vision system for locating the initial position of the structure onthe cradle 130. The gantry vision system may also be used for collisionavoidance.

Precise positioning of the keel structure over the cradle 130 is notrequired. The keel structure need only be positioned over, and loweredinto, arms 132 of the cradle 130. The arms 132 are contoured to guidethe keel structure to an initial position.

The cradle 130 may be divided into multiple segments 130 a-130 d. Inthis example, the fore keel structure is placed onto two segments 130 aand 130 b, which move in tandem together to prevent any preloads on thekeel structure. The cradle 130 may have an x, y, and z axis positioningsystem (not shown) to refine the position of the keel structure relativeto the arms 132 (consequently, the position of the cradle 130 relativeto the floor markings need not be precise).

In the meantime, a mid keel structure is being moved into the feederline area 220. After the gantry 140 lowers the fore keel structure ontothe cradle 130, it is returned to the feeder line area 220.

The gantry 140 is moved over the mid keel structure as shown in FIG. 2F,and then the gantry 140 moves the mid keel structure over the cradle130. The gantry 140 then lays the mid keel structure onto segment 130 cof the cradle 130, as shown in FIG. 2G. The x, y, and z axis positioningsystem refines the position of the mid keel structure.

An aft keel structure is supplied and positioned on segment 130 d of thecradle 130. As the aft keel structure is being positioned, a floor gridis moved into the feeder line area 220 (FIG. 2H). The gantry 140 movesthe floor grid and positions it onto the mid and aft keel structures, asshown in FIG. 2I.

The gantry 140 then moves fore, mid and aft side panels onto the keelstructures, as shown in FIGS. 2J, 2K and 2L. The side panels are secured(e.g., pinned) to the keel structures.

The gantry 140 then moves nose, fore, mid and aft crown panels onto theside panels, as shown in FIGS. 2M and 2N. The crown panels are securedto the side panels.

The indexing of the side and crown panels may be performed by usingdeterminant assembly holes, which are accurately drilled into structuralcomponents such as frames, stanchions, and floor beams. The use of thedeterminant assembly holes is described in greater detail below inconnection with FIG. 4.

The panels and keel structures are then fastened together. A set of fourtall robots 150 a are commanded to move from the robot holding area 230to the first cell 210, as shown in FIG. 2O. The tall robots 150 a arebrought in to perform high-reach operations. The tall robots 150 a thenposition themselves about the fuselage, as shown in FIG. 2P. The robots150 a may identify determinant holes in the fuselage or they mayidentify other features. The robots 150 a use these features toestablish individual frames of reference with respect to the fuselage.Subsequent movements and robotic operations are performed with respectto those reference frames.

Once positioned, the tall robots 150 a perform longitudinal splices andupper circumferential splices (the short robots 150 b will perform theremainder of the circumferential splices). During splicing, skin panelsare fastened to skin panels. For longitudinal splices, a lap join may beused to fasten skin panel to skin panel. Internal structures such asstringers and shear ties may be added to the joins. For circumferentialsplices, a butt join may be used to fasten skin panel to skin panel.Internal structures such as splice plates, shear ties, stringers andstringer splices may also fastened together with the butt joins.

After the tall robots 150 a have performed the long-reach operations,the short robots 150 b are brought in from the robot holding area 230(FIG. 2Q) to perform low-access operations. The short robots 150 bestablish individual frames of reference with respect to the fuselage,and perform subsequent movements and lower circumferential splices withrespect to those reference frames

While the fastening operations are being performed, other fuselages maybe assembled. As shown in FIG. 2Q, a second cradle 130 is moved to asecond assembly cell 210, and keel structures of a second fuselage areloaded onto the second cradle 130.

As shown in FIG. 2R, assembly is being performed on two additionalfuselages. After the tall robots 150 a have finished its operations onthe fuselage in the first cell 210, those robots 150 a may be moved tothe second assembly cell 210 to perform operations on the secondfuselage. Additional tall robots 150 a may be moved to a third cell toperform operations on a third fuselage. After the short robots 150 bhave performed their operations on the fuselage in the first cell 210,they may be moved to the second cell 210 or back to the robot holdingarea 230.

As shown in FIG. 2S, additional fuselages are assembled until all sixcells 210 are occupied. As shown in FIG. 2T, when assembly of a fuselagehas been completed, that completed fuselage is moved off the floor 120by the cradle 130. The completed fuselage may be moved to a location forcleaning, sealing and painting.

Thus disclosed is an automated assembly facility using movable cradles,gantry and multiple robotic systems working in tandem for completeconcurrent integration of multiple fuselages. Because the fuselageassembly is largely automated, dependence on manual labor is greatlyreduced. Consequently, the production environment is more stable.

The floor space of the assembly facility is reconfigurable. Since nofixtures or jigs are secured to the assembly floor, assembly cells canbe relocated, and spacing between cells can be changed. Thereconfigurable floor space also helps with multiple product lines. Ifthe supply chain of one model becomes constrained, the floor space maybe reconfigured to produce other models until the supply chain recovers.

The assembly facility is scalable. To increase production rate, or toconvert to a new product line, floor space is either expanded orreconfigured. Existing robots maybe used to service the new cells.

Different types of fuselages may be built in different cells at the sametime. As the robots move from one cell to another, their programmingand/or end effectors may be changed.

Reference is now made to FIG. 3, which illustrates an example of a robot150. The robot 150 includes an end effector 310 that is configured tomake fuselage splices. The end effector 310 may be further configured toperform operations including, but not limited to, inspection, sealantapplication, and electromagnetic clamping.

The robot 150 may have a positioning system 320 for translating andorienting the end effector 310. For example, the combination of an x-y-zmover 322 and a spherical wrist 324 provides six degrees of freedom forpositioning the end effector 310 with respect to a surface of afuselage. A robotic arm 326 may enable the end effector 310 to reach thebelly and crown of the fuselage.

The robot 150 may include an AGV 330, which provides additional degreesof freedom. The AGV 330 moves the robot 150 across the assembly floor.The AGV 330 also positions the robot 150 along the fuselage duringoperation.

The robot 150 may include a vision system 340 that assists with thepositioning. For example, the robot 150 is programmed to move to a roughposition on in an assembly cell. The vision system 340 then detects keyfeatures (e.g., edge of skin panels, holes drilled on the longitudinaland circumferential splices) that provide a frame of reference.

Once the reference frame has been established, the robot uses thatreference frame to move to a “work envelope.” For instance, the AGV 330may move the robot 150 a precise offset distance with respect to thereference frame. The robot may perform drilling and fastening operationsat all locations within the work envelope.

A controller 350 may execute an NC program that commands the robot 150to perform its operations. In some embodiments, the operations mayinclude a one-up fastening process, which may be performed for eachlocation along a splice.

Reference is now made to FIG. 4, which illustrates a one-up fasteningprocess. At block 410, a splice structure is clamped up using, forinstance, an electromagnet mounted on the robot's end effector 150 and asteel plate on the opposite side of (inside) the fuselage. The steelplate may be positioned manually or robotically using key features onfuselage frames. In a one-up process, the clamp not only holds two ormore parts together but also prevents interlaminar burr from gettingcaught in between the clamped parts. It also prevents leakage of sealfrom the clamped parts. Because no chips or burrs are caught between theclamped parts, the one-up process improves fatigue strength of thejoins.

At block 420, a hole is drilled and countersunk. At block 430, thedrilled hole and countersink are inspected. At block 440, a fastener isinserted in the drilled hole. If the join is bolted, a sealant may alsobe applied. These steps may be performed robotically.

At block 450, the fastener is terminated. For instance, if the fasteneris a bolt, a collar and nut may be placed onto the threaded end of thebolt and tightened. If the fastener is a rivet, a bucking bar may beused to upset (or buck) the free end. The fastener termination may beperformed robotically or manually.

At block 460, the splice structure is declamped. Thereafter, the endeffector 310 is positioned at a new location along the splice. Thefunctions at blocks 410 to 460 are repeated.

Once all splices have been made in the robot's work envelope, the AGV330 moves the robot 150 along the fuselage to a new work envelope.Additional splices are performed in the new work envelope.

FIG. 5 illustrates a method of assembling a panelized fuselage in asingle upright build position. In some embodiments, the panels includeskin and underlying stiffening structure. The panels may also includeintegrated frames (e.g., hoop frames).

Reference is made to FIG. 6A and block 510 of FIG. 5. A keel structure610 is loaded onto a cradle 130. In some embodiments, the keel structure610 may include keel panels and an integrated keel beam. The keelstructure 610 may be loaded as a unitary structure or it may be loadedin sections (FIGS. 2C to 2H show a keel structure that is loaded insections). The keel structure 610 is then aligned and leveled.

Reference is made to FIG. 6B and block 520 of FIG. 5. Assemblystanchions 630 are attached to a floor grid 620, and the stanchions 630are lowered on panels of the keel structure 610. The floor grid 620includes floor beams, vertical stanchions and other components (e.g.,seat tracks, floor fittings, and intercostals). The assembled structureis positioned over, and lowered onto the keel structure 610, and theassembly stanchions 630 are fastened to the keel structure 610.

Reference is made to FIGS. 6C and 6D and block 530 of FIG. 5. Lower(e.g., side) panels 640 are loaded onto, and assembled to, floor beamsof the floor grid 620. The stanchions 630, the keel structure 610 andthe cradle 130 are used to support the lower panels 640. In someembodiments, the lower panels 640 may loaded as a unitary structure. (Inthe example shown in FIGS. 2J, 2K and 2L, the lower panels are loaded insections.) In the example illustrated in FIGS. 6C and 6D, a left lowerpanel 640 is loaded and attached (FIG. 6C) and then a right lower panel640 is loaded and attached (FIG. 6D). A spreader bar 650 may be used tosupport the free ends of the lower panels 640.

Additional reference is made to FIG. 6E and block 540 of FIG. 5. Upper(e.g., crown) panels 660 are loaded. The upper panels 660 may be loadedas a unitary structure, or they may be loaded in sections (as shown inFIGS. 2M and 2N). In FIG. 6E, the upper panels 660 are loaded onto thespreader bar 650 and assembled to the lower panels 640.

Determinant assembly (DA) holes may be used to locate the variouspanels. A first set of DA holes may be used to locate the floor grid 620on the assembly stanchions 630; a second set of DA holes may be used tolocate the assembly stanchions 630 on the keel structure 610; a thirdset of DA holes may be used to locate the lower panels 640 on the floorgrid 620; and a fourth set of DA holes may be used to locate the upperpanels 660 with respect to the lower panels 640. Once the DA holes havebeen aligned, mechanics may manually pin the determinant assembly holes.

By following the method of FIG. 5, a full contour of the fuselagesection is obtained prior to splicing.

In some embodiments, all DA holes are internal on the fuselage structure(mostly on the inside stiffening structure such as frames, stanchionsand floor beams), and no DA holes are located on the keel structure orany external structure of the fuselage skin panels. These DA locatingholes may be precision machined on the internal structure.

In some embodiments, forward and aft bulkheads of the fuselage sectionmay be used as initial indexing planes. The planes are used to maintaina perpendicularity relationship between the bulkheads and the keelstructure. This ensures that all integration of panels results in a truecylindrical shape.

The invention claimed is:
 1. A method of assembling a panelized aircraftfuselage, the method comprising: loading a keel structure on a cradle;attaching stanchions to a floor grid; positioning the floor grid andstanchions over the keel structure and attaching the stanchions to thekeel structure; obtaining a full fuselage contour including locatinglower panels on the floor grid while using the cradle, the floor grid,and the keel structure to support the lower panels, and locating upperpanels on the lower panels; and fastening the lower panels to the keelstructure and the upper panels, wherein the fuselage is assembledupright from the keel structure without changing orientation of thefuselage.
 2. The method of claim 1, further comprising moving the cradleinto a selected one of a plurality of cells on an assembly floor priorto loading the keel structure on the cradle.
 3. The method of claim 2,further comprising using a moveable gantry to move the keel and lowerand upper panels across the assembly floor to the selected cell.
 4. Themethod of claim 2, further comprising plurality of robots for performingfuselage fastening operations into the selected cell, and using therobots to fasten the lower and upper panels.
 5. The method of claim 4,wherein the robots are programmed to use fuselage features to establishindividual frames of reference, and perform subsequent movements androbotic operations with respect to those reference frames.
 6. The methodof claim 4, further comprising using automated guide vehicles to movethe robots and the cradle.
 7. The method of claim 4, wherein each robotincludes an end effector for performing fuselage fastening operations, apositioning system for positioning the end effector, and a controllerprogrammed to control the positioning system to move the end effectorthrough a sequence of fastening locations and control the end effectorto perform the fastening operations at those locations in the sequence.8. The method of claim 4, wherein the robots include tall robots forperforming longitudinal splices and circumferential splices on upperfuselage portions, and short robots for performing circumferentialsplices on lower fuselage portions.
 9. The method of claim 1, wherein afirst set and a second set of determinant assembly (DA) holes are usedto locate the stanchions on the floor grid and the keel structure,respectively; wherein a third set of DA holes are used to locate thelower panels on the floor grid; and wherein a fourth set of DA holes areused to locate the upper panels with respect to the lower panels. 10.The method of claim 9, wherein as the respective sets of DA holes arealigned, the floor grid is pinned to the stanchions, the stanchions arepinned to the keel structure, the lower panels are pinned to the floorgrid and stiffened by the floor grid, and the upper panels are pinned tothe lower panels to obtain the full fuselage contour.
 11. The method ofclaim 10, wherein the pinning of the floor grid to the stanchions, thestanchions to the keel structure, the lower panels to the floor grid,and the upper panels to the lower panels is performed manually.
 12. Themethod of claim 9, wherein all the sets of the DA holes are internal onthe fuselage.
 13. The method of claim 1, wherein the upper and lowerpanels include skin and underlying stiffening substructure.
 14. Themethod of claim 1, wherein the keel structure is loaded in segments. 15.The method of claim 1, wherein the lower panels are separated with aspreader bar; and the upper panels are located on the spreader bar.